Current Assignments Homework 3 is due tonight. Iteration and basic functions. Exam 1 on Monday.

Recursion (Frames and The Stack) void foo( int x) x = 0 { if ( x < 4 ) { // Recursive step cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; // Base case } void foo( int x) x = 1 { if ( x < 4 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; } void foo( int x) x = 2 { if ( x < 4 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; } void foo( int x) x = 3 { if ( x < 4 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; } void foo( int x) x = 4 { if ( x < 4 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; } foo(0); Hello 0 Hello 1 Hello 2 Goodbye 3 Goodbye 2 Goodbye 1 Hello 3 Goodbye 0

Recursion (Frames and The Stack) void foo( int x) x = 0 { if ( x < 2 ) { // Recursive step cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; // Base case } void foo( int x) x = 1 { if ( x < 2 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; } foo(0) Hello 0 Hello 1 Goodbye 0 Goodbye 1 Hello 1 void foo( int x) x = 1 { if ( x < 2 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; } Goodbye 1 void foo( int x) x = 2 { if ( x < 2 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; } void foo( int x) x = 2 { if ( x < 2 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; } void foo( int x) x = 2 { if ( x < 2 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; } void foo( int x) x = 2 { if ( x < 2 ) { cout << “ Hello “ << x <<endl; foo(x+1); cout << “ Goodbye ” << x << endl; } return; }

Recursion Program Trace Fib Fact Visualization of Recursion with Java

Exam 1 Anatomy of a Computer Types and Variables Operators –Mathematical –Boolean Control Structures –Selection (if…else, switch) –Iteration(while, for)

Exam 1 Input and Output –cin, cout, >>, << Functions –Calling Functions –Function Prototypes –Function Definitions –Function overloading

Sample Problem Find the bug in this code: #include using namespace std int main( ) { cout << "hello world!" << endl; return 0; }

Sample Problem Find the bug in this code: #include using namespace std; int main( ) { double width, area; cout<<"Enter the width of the square: "; cin >> width; Area = width * width; cout << "The area of the square with the width = " << width << " is " << Area << endl; return 0; }

Sample Problem Find the bug in this code: #include int main() { int i = 30; while( i != 100 ) { i++ if ( i == 100 ) { i = i – 1; } cout << i << “ “ << endl; }

Sample Problem Find the bug in this code: #include int test( int n ); int main() { int n = 5; cout << test( n ); return 0; } int test( int ) { return (n+1); }

Sample Problem Find the bug in this code: #include (iostream) int main() { int i = 30; while( i < 100 ) { i++ if ( i == 100 ) { i = i + 1; } cout << i << “ “ << endl; }

Sample Problem Calculate the value of n: int a = 3.3, b = 2.7, p = 8.7, q = 5.4; double n = p/b + q/a %;

Sample Problem Calculate the value of n: int a = 3.3, b = 2.7, p = 8.7, q = 5.4; double n = (p/b + q/a) % 3; Ans: 2

Sample Problem Give the value of n after this code: int n = 3, a = 2, b = 7, c = 4; if (b>6 && c<4 || a==0) { n = n + 5; } if (a>3 && b>5 || c<=9) { n = n + 20; } if (c>2 || a<8 && b==7) { n = n - 5; } Ans: 18

Sample Problem Give the value of n after this code: int n = 3, a = 2, b = 7, c = 4; if (b>6 && c<4 || a==0) { n = n + 5; } if (a>3 && b>5 || c<=9) { n = n + 20; } if (c>2 || a<8 && b==7) { n = n - 5; } Ans: 18

Sample Problem What does this program print? for ( int i = 0; i < 5; i++ ) { for ( int j = 0; j < i; j++ ) { cout << j << “ “; } cout << endl; } Ans:

Sample Problem What does this code print? #include using namespace std; int main() { int n = 1; for ( int i = 1; i < 6; i++ ) { n *= i; cout << n << " "; } Ans:

Sample Problem What does this code print? #include using namespace std; int main() { int n = 1; for ( int i = 0; i < 6; i++ ) { n *= i; cout << n << " "; } Ans:

Sample Problem What does this code print? int n = 1; while ( n < 5 ) { for ( int i = 1; i < 5; i++ ) { cout << n++ << " "; cout << ++n << " "; } Ans:

Sample Problem Write a program that sums the even numbers between 1 and 100 inclusive. Ans: #include int main() { int sum = 0; for ( int i = 1; i <= 100; i++ ) { if ( i % 2 == 0) { sum = sum + i; }

Sample Problem What does the following code print: char foo = ‘b’, bar = ‘a’; n = 4; while ( n < 20 ) { if ( n % 4 == 0) { cout << foo; } if ( n % 2 == 0) { cout << bar; } n = n + 2; } cout << ‘c’; Ans: baabaabaabaac What does the following code print: char foo = ‘b’, bar = ‘a’; n = 4; while ( n < 20 ) { if ( n % 4 == 0) { cout << foo; } else if ( n % 2 == 0) { cout << bar; } n = n + 2; } cout << ‘c’; Ans: babababac

Sample Problem What does the following code print: #include using namespace std; int cow( int ); int sheep( int ); int main() { int n = 1; for ( int i = 1; i < 3; i++ ) { cout << "quack " << endl; cow( i + 1); } Ans: quack moo moo baa moo baa baa quack moo moo baa moo baa baa int cow( int x ) { for ( int i = 0; i < 3; i++ ) { cout << "moo "; sheep( i ); } return 0; } int sheep( int x ) { for ( int i = 0; i < x; i++ ) { cout << "baa "; } return x; }

Sample Problem What does the following code print: #include using namespace std; int test( int x, int y ); int main() { int j = 1; while( test( j, j ) < 8*j ) { cout << j << " "; j = j * 2; } return 0; } int test( int x, int y ) { return (x * y); } Ans: 1 2 4